Failed Blackbird Nest

I've been away for a few days and the boss has sent me a photo of an empty nest. Almost certainly the blackbird nest I blogged about a week ago is now abandoned, not from disturbance but more probably from predation as the nest is empty. Who the predator was is unknown. Unlikely to be a cat as the nest is difficult to get to and doesn't seem to be damaged. Possibly magpies or jackdaws, both of which are in the garden. Maybe even a squirrel, but I've not seen a grey squirrel for some time now.